This invention relates in general to apparatus for separating suspended settleable and flotable substances from a flow of liquid in order to clarify the liquid. More particularly, the invention pertains to apparatus of the type in which the liquid is directed through passages defined by several spaced rows of spaced plates or vanes. The suspended substances in the liquid contact the vanes and are directed out of the flow and into upright ducts or channels located between the rows of vanes and existing as a result of upright baffles which are positioned adjacent the upstream ends of the vanes. Apparatus of this general type is disclosed in Pielkenrood U.S. Pat. No. 3,837,501.